As well known to those in the art, in heating systems using boilers which have been generally used, hot water, which is heated by combustion of oil or gas used as a heat source, circulates through a radiating pipe, thus heating a desired place. To construct such a heating system, an insulation layer is formed on a planar support surface, and a heat storage layer, which comprises gravel and coarse sand, is thereafter formed on the insulation layer. Subsequently, a radiating pipe, which comprises a metal pipe or a synthetic resin pipe having superior heat conductivity, is evenly arranged on the insulation layer. The radiating pipe is covered with and finished by mortar. Thus, heating operation is realized by hot water circulating the radiating pipe. However, in the conventional heating system using the boiler, there is a problem of noise due to circulation of water. Furthermore, due to existence of the boiler and a fuel tank for containing oil, a large installation space is required. In the case that gas is used as fuel, due to the hazardous nature of the gas, there is an inconvenience in that periodic maintenance and regular monitoring is required.
To solve the above-mentioned problems, heating apparatuses, which have a special cover that securely closes a heating pipe charged with liquid heating medium and guides a heating wire, which is prevented from being directly exposed to the heating medium liquid, were proposed in Korean Utility Model Registration No. 326738 and Korean Utility Model Registration No. 331132. However, in these apparatuses, only a single strand of heating wire is placed through the radiating pipe, and the cover serves merely to close the radiating pipe and to guide the heating wire. Therefore, there are problems of fire hazard and of heat loss due to the heating wire being exposed to the outside. Furthermore, even if several strands of heating wires are provided, because the heating wires may be incorrectly connected to outside electric wires, there is a possibility of shorting. That is, there is a problem in that the operation of the prior art heating apparatus is unsafe.